The present invention relates to a gas lighter comprising a safety ignition system, also referred to as a "child resistant" lighter, that is to say can not be ignited by a child of less than five years old.
A gas lighter generally comprises a reservoir for containing liquefied petroleum gases, a valve mounted on the reservoir permitting gas to leave the reservoir, an opening and closing system for the release of gas operated by a lever, a system of regulation of the release of gas as well as the ignition system. In a known way, the ignition system comprises a pyrophoric flint co-operating with a spark wheel and the lighter also comprises a protective cap. The spark wheel is mounted on an axis between two operating wheels which are attached to it. The spark wheel has a cylindrical shape and each of the operating wheels comprises a disk having a diameter slightly greater than that of the spark wheel. The rims of the operating wheels comprise unevennesses which make then rough. Thus, a user can easily operate the spark wheel with a finger, because the finger does not slide on the operating wheels.
When the spark wheel, being in contact with the flint, is rotated by operation of the operating wheels by a digit of the user, a spray of sparks is created and is followed by the action of the same digit against the gas opening lever which releases a quantity of gas. The spray of sparks ignites the gas, producing a flame which forms above the cap.
Such a system requires a positive action on the part of the user to produce aid maintain a flame and requires two independent movements one after the other--rotation of the spark wheel and action on the gas opening lever--to produce a flame.
However, it is desirable to increase the difficulty of operating such lighters so that children younger than five years old are not able to produce a flame with such lighters.
Lighters already exist providing a supplementary difficulty which must be overcome to produce a flame and several patents or patent applications describe such lighters. For example, patents U.S. Pat. No. 5,125,829, U.S. Pat. No. 5,002,482 or international patent applications WO 93/17282, WO 95/04247.
Most of the lighters described in these documents comprise, compared to conventional lighters, a supplementary device making access to the operating wheels of the spark wheel more difficult, or by blocking movement of the gas opening lever.
In this way, these lighters comprise a complex structure involving an increased cost of manufacture. Furthermore, the use of some of these lighters is complicated and requires a particular method of use. Even adults can find several difficulties in the operation of such lighters and/or need preliminary instructions.
U.S. Pat. No. 5,096,414 concerns a lighter which does not contain operating wheels fixed to the spark wheel, but two flat discs having a diameter greater than that of the spark wheel, and freely mounted to rotate about an axis corresponding to that of the spark wheel. In this case operation of the spark wheel is achieved directly by the flesh of the digit of the user, after deformation between the two free discs.
In a similar system, the axis of the spark wheel comprises a polygonal section, and the operating wheels comprise corresponding holes of polygonal cross section, which co-operate with the axis. These polygonal sections permit the rotational connection of the operating wheels and the spark wheel when a sufficient radial pressure is exercised on the operating wheels. A disadvantage of this system is that it results in the rapid wear on the flats of the axle and the holes such that the operation of the operating wheels becomes more and more difficult with time. Moreover, the force exercised on the operating wheels is difficult to control. Furthermore, this force has to be applied in a perfectly radial manner in order for the operation of the spark wheel to take place, which necessitates the application of increased pressure by the user.
An objective of the present invention is to provide a lighter which is easily operated by an adult, but very difficult to use by a child especially a child of less than five years old, and which remedies the disadvantages of the prior art lighters.
Another objective of the invention is to provide a reliable security system which is inviolable and constant in operation throughout the life of the lighter.
Another objective of the invention is to have the functioning of the lighter as close as possible to the functioning of a traditional lighter, in which the "unblocking" action is realized in the same place as the ignition action, in such a way that the user has no need either for preliminary instructions or practice in order to operate the lighter.